Preliminary studies from our laboratory have shown that we can achieve an enhancement of the NK activity using a classical conditioning paradigm. We believe that conditioned enhancement of IFN levels and NK activity and will try to establish the optimal conditions for the conditioned enhancement. The variables which we would like to consider to optimize the elevations are: 1) The schedule of unconditioned stimulus (US)/conditioned stimulus (CS) association trials, 2) The length of exposure to CS, 3) The number of association trials, 4) The time between association trial and test and 5) Dose of poly I:C (suboptimal doses). We will also attempt to determine the extinction of this response with repeated exposure to CS. These studies are important because they explore the connection between mind and body, and resistance to disease. It has become increasingly apparent that many diseases are multifactorial and psychosocial aspects may play an important role in the etiology of disease. We would like to see this connection between the CNS and resistance to disease exploited for the benefit of the health of the individual, instead of always being a liability (in terms of suppressed immunocompetence when challenged by adverse circumstances). We feel that a conditioned enhancement of immunocompetence may be a possibility for deriving benefit from this connection between mind and immunity.